Railway traffic controlling apparatus



Jan. 7, 1936. H s, YOUNG 2,027,216

RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Oct. 13, 1952 2 Sheets-Sheet 1 INVENTOR Henry Siwzy.

N r BY QRv/LMA' '10 1115 ATTORNEY Jan. 7, 1936. I H. s. YOUNG RAILWAY TRAFFIC CONTROLLING APPARATUS Y Filed Oct. 13, .1932 2 Sheets-Sheet 2 .Young:

HIS A TTORNEY Patented Jan. 7, 1936 UNITED STATES PATENT OFFICE RAILWAY TRAFFIC CONTROLLING APPARATUS A 12 Claims. ('01. 246160) My invention relates to railway traffic controlling apparatus, and particularly to apparatus of the type involving a railway switch and signals governing trafiic movements over the switch.

Morespecifically, my invention relates to apparatus wherein a train approaching a spring .movements in the second direction over the switch only if the switch is unlocked.

I will describe two forms of apparatus embodying my invention, and will then pointout the novel features thereof in claims.

In the accompanying drawings, Fig. l is a diagrammatic view showing one form of apparatus embodying my invention. Fig. 2 is a diagrammatic view showing a modification of the apparatus shown in Fig. 1, and also embodying my invention.

Similar reference characters refer to similar parts in each of the views.

Referring to the drawings, the reference character X designates a stretch of single tracl; railway which is connected with tracks Y and Z by. means of a switchF. In Fig. 1, tracks Y and Z may be either a stretch of double track or they may be passing tracks, as shown in Fig. 2, the

opposite ends of which are connected with stretch X by a second switch F Each of these switches may be biased to its normal position, in which it is shown, by some suitable means which may, for example, be of the well known spring type. Each of these switches may be manually movable to its reverse position by suitable means not shown in the drawings, and may also be movable to its reverse position by a train going over the switch in the trailingdirection, that is, switch F may be movable to its reverse position by a train going over it from track 2 to stretch X, and switch F? may be movable to its reverse position by a train going over it from track Y to stretch X.

Rails l and. l of stretch X and of tracks Y and Z are divided by means of insulated joints 3 into sections A-B, BC, CD, and C In Fig.

7 2, there is also an additional section A track circuit is provided for each of these sections, and includes a track'battery 4 connected across the rails adjacent one end of the section and a track relay designated by the reference character R with a distinguishing exponent and connected across the rails'adjacentthe other end of the section.

Signals, each of which is designated by the ref- 5 erence character S with a distinguishing exponent, govern tramc movements in both directions over switches F and F SignalsS and S govern trafi'ic movements in the trailing direction over switch F from tracks Y and Z, respectively, to stretch X, and signal S governs trailic movements in the opposite or facing direction over switch F from stretch X to track Y. Similarly, signals S and S shown in Fig. 2, govern traffic movements in the trailingdirection over switch F from tracks of the color light type, although it is to be understood that my invention is not limited to this particular type of signals. In Fig. 1, the signals S are shown having a red or stop lamp R and a green lamp G indicating clear. In Fig. 2, the signals are shown having also a yellow lamp Y indicating caution.

Circuits and other parts of the apparatus are shown for controlling switch F and signals S S and S Switch F shown in Fig. 2, and signals S*, S and S associated withthis switch may be controlled similarly to switch F and the associated signals S S and S respectively, also shown in Fig. 2.

A look bar at is rigidly secured to switch F for engagement by a dog a, by means of which the switch may be locked inits normal position only. Dog a is actuated by a motor G which may be of any suitable type but which, as here shown, is an'electric motor having an armature dog a, is in its normal position out of engagement with bar (2. Dog a actuates a contact 41 which is closed only when'dog a is out of engagement with bar d, and also actuates a contact 26 which is closed only when dog a is in its final position for locking bar 11.

Movement of motor G andclearing of signals -S are controlled by trains approaching switch F is train-approaching switch F in the facing 5.5-

direction, that is, from left to right as shown in the drawings, will set motor G into operation to lock switch F in the normal position, whereas a train approaching switch F in the trailing direction, that is, from right to left will, in Fig. 1, set motor G into operation to unlock switch F if that switch is locked. A train approaching switch F in the facing direction, which I will also assume to be the eastbound direction, will cause signal S to clear as soon as motor G has locked switch F in the normal position. A train approaching switch F in the trailing or westbound direction will cause signal S or signal S to clear when switch F is unlocked. In Fig. 2, a train, after moving over switch F in the facing direction, will set motor G into operation to unlock the switch, and hence a train approaching switch F in the trailing direction will, in Fig. 2, merely clear signal S or signal S since switch F will be already unlocked.

' Switch F actuates a circuit controller commonly known as a point detector, which in Fig. 1 has only one contact I, and which in Fig. 2 has a second contact 63 in addition to a contact 1. Each of these contacts is closed only if the switch points of the associated switch are in their proper condition while the switch is in its normal position.

A hand crank N is provided adjacent switch F primarily for emergency use by a trainman to manually move dog 11 out of engagement with bar (1 when it becomes necessary to manually reverse the switch for a traffic movement in the eastbound direction from stretch X to track Z. For this use, the trainman will place crank N in the position in which it is shown in dash lines in the drawings, thereby displacing contact 8 to its open position 7'. He will then operate crank N to disengage dog a from bar (1. Contact 8 in Fig. 1, upon becoming opened, breaks the pick-up and stick circuits for a relay I which, being thereby deenergized, opens the operating circuits for motor G. Relay I also controls a pick-up circuit for a track stick relay R for section B-C. In the arrangement shown in Fig. 2, contact 8, upon becoming opened, breaks the pick-up and stick circuits for a relay W which controls motor G.

Referring to Fig. 1 ofthe drawings, a train, upon approaching switch F from the left, that is, in the facing direction, will cause an approach relay P to become energized, and this will cause motor G to operate dog a into engagement with bar d to lock switch F in the normal position. Upon completion of this locking operation for switch F a slow release relay H will become energized for clearing signal S The train, upon then passing signal S will cause a directional stick relay I to become energized. This relay, when energized, prevents the clearing" of signal S while a train is moving in the eastbound direction in section CD, and permits the clearing of signal S if another train is in section C A westbound train approaching switch F on track Z will cause a second approach relay P to become energized for causing motor G to oper ate dog' a out of engagement with bar d if dog a has been operated to the position for locking bar d. ,With switch F thus unlocked and with relay P energized, a signal control relay 1-1 will become energized for clearing signal S A westbound train, upon passing signal S? while signal S .is. displaying its proceed indication, Willcause a second directional stick relay I to become energized. The purpose of this relay is to prevent any automatic action toward locking switch F or clearing signal S while a train is moving in the westbound direction in section A-B. A push button contact U is provided for use when necessary to deenergize relay 1, after a train movement from track Z to stretch X, for permitting motor G to lock switch F and for permitting signal S to clear for the train to proceed eastward to track Y.

Relays 1-1 1-1 and P are of the slow releasing type in order that they may control the directional relays I and I in a given manner by circuits which will be traced hereinafter.

Referring now to Fig. 2, each of the signals S is here shown controlled by a slow release neutral relay designated by the reference character H with a corresponding exponent, and by a polarized relay designated by the reference character T with a corresponding exponent. When an eastbound train approaches switch F relay T for controlling signals S and S will become deenergized, causing relay H to also become deenergized. Relay H upon becoming deenergized, causes signal S to display the stop indication. The deenergization of relays T and H causes control element 59 of a time element device M to become energized. Device M, upon the lapse of a measured period of time after be coming energized, closes its contact 60 which causes relay W to become energized. Relay W then completes a circuit for causing motor G to operate dog a to lock the bar cl. Upon the completion of this operation of dog a, relay H will become energized and. cause signal S to display a caution or a clear indication according as relay T is energized in the reverse or the normal direction, respectively. After the eastbound train has proceeded through sections AB and 13-0, relay W will become energized and cause motor G to operate dog a to unlock bar d. Relay l-l will then become energized and cause signal S to display either a caution or a clear indication according as relay T is energized in the reverse or the normal direction, respectively.

Traffic direction stick relays I and I are in part controlled similarly to the corresponding relays of Fig. 1. Relay I in turn, controls a third directional stick relay I The control circuit for relay T for signal S is included in order to show how the control of this relay is affected by the apparatus associated with switch F Signal S will be controlled by relay T similarly to the manner in which signal S is controlled by relay T Switch F may also be of the spring type, and, may be controlled similarly to the manner in which switch F is controlled. Signals S S and S may be controlled similarly to signals S S and S respectively. Relay T would then be controlled by the apparatus at switch F similarly to the manner in which relay T is shown controlled by the apparatus at switch F Having described, in general, the arrangement and location of the various parts of the apparatus embodying my invention, I will now describe in detail the. operation of the appartus.

As shown in Fig. 1, all parts are in their normal condition, that is, switch F is in its normal position, each of the signals S is displaying a stop indication; each of the track sections is unoccupied; with the track sections unoccupied, the track relays R are energized; dog a is out of engagement with bar d; and relays H, P, I and I are deenergized. The red lamp R of each of the signals S is lighted, for displaying the stop indication, by a circuit which includes the back point of a contact ll of its control relay H. Relay I is energized by its stick circuit which passes from terminal I) of a source of current'not shown in the drawings, through point detector contact 1 of switch F contact 8 operated by crank N, contact 9 of relay I and the Winding of relay I to terminal of the same source of current. Relay R is energized by both its pick-up and its stick circuit. The pick-up circuit for relay R includes track battery 4 and the rails of section B-C, and passes through front contact 6 of relay 1? and the Winding of relay R The stick circuit for relay R is the same as the pick-up circuit except that it includes contact of relayR? instead of contact 6 of relay I I will now assume that an eastbound train enters section AB, causing relay R to become deenergized. Relay R thereupon completes a circuit for, energizing approach relay P passing from terminal I), through contact I of switch F back contact 92 of relay P back contact l3 of relay H back contact I4 of relay I contact l5 of relay'R contact I6 of relay R and the winding of relay P to terminal 0. Relay P upon becoming energized, completes a reverse opcrating circuit for motor G, passing from terminal I), through contact 1 of switch F contact I! to terminal 0. Motor G thereupon moves dog a into position to engage and lock bar 0!. Upon the completion of this locking movement of dog a, contact 2| opens the reverse operating circuit traced for motor G, and relay H becomes energized by a circuit passing from terminal b, through contact 25 of relay H contact 26 of dog a, contact 21 of relay P andthe winding of relay H to terminal 0. Relay I-I thereupon opens, at the back point of its contact ll, the circuit for red lamp R'of signal S and closes, at the front point of its contact I I, the circuit for green lamp G of signal S The train, upon entering section B-C, deenergizes relay R which thereupon opens, at its contact I5, the circuit traced for relay P Relay P upon becoming deenergized, opens, at its 7 contact 21, the circuit traced for relay H Relay H being slow releasing, does not at once open its contact 30 at the front point, and hence a pick-up circuit is completed for a brief period 55 of time for energizing relay I passing from terminal b, through contact 28 of relay R front point of contact 30 of relay H and the winding of relay I to terminal 0. Relay I upon becoming energized, completes its own stick circuit passing from terminal b, through contact 28 of relay R contact 3| of relay I and the winding of relay I to terminal 0. Relay R upon becoming deenergized, also completes a pick-up circuit for relay I which is the same asthe stick 65 circuit previously traced for this relay except that it includes contact ID of relay R instead of contact 9 of relay 1 i As the train enters section CD, relay 1'1. becomes deenergized, thereby completing a second stick circuit for relay I passing from terminal b, through contact 29 of relay R back point of contact 30 of relay H contact 3| of relay I and the winding of relay I to terminal 0. Relay I ;therefore continues energized until the train contact 39 is open in a circuit for energizing relay H and hence relay H can not become energized while the train is receding from signal S Signal :3. can therefore not clear as long as the eastbound train is in section CD. 5 If, however, a westbound train enters section C=D while the eastbound train is still in section CD, approach relay P will become energized by a circuit passing from terminal b, through contact 32 of relay P contact 33 of relay R contact 34 of relay R contact 35 of relay R contact 31 of relay I and the wLnding of relay P to terminal 0. With relay P thus energized, a circuit will be completed for causing motor G to return dog a to its normal position out of engagement with bar d. This circuit for motor G passes from terminal 12, through contact 23 of relay P contact IQ of relay I armature l8 of motor G, contact 24 of relay P contact 2| of motor G in its reverse position, and field winding 22 of motor G to terminal 0. As soon as motor G completes the operation of dog a to its unlocking position, relay H will become energized by a circuit passing from terminal I), through contact 46 of relay H contact 4'1 ofdog a, contact 48 of relay P and the winding of relay H to' terminal 0. Relay H upon becoming energized,' opens, at the back point of its contact H, the circuit for the red lamp of signal S and completes, at the front point of its contact I I, the circuit for green lamp G of signal S thus permitting the westbound train in section C D to proceed while an eastbound train is still in section CD.

The westbound train, upon passing signal S deenergizes relay R which then opens, at its contact 34, the circuit traced for relay P Relay l? thereby becomes deenergized but, on account of being slow releasing, causes a pick-up circuit to be completed for a brief period of time for 0 energizing relay I passing from terminal 2), through contact 40 of relay R front point of contact 42 of relay P the winding of relay I and push button contact U to terminal 0, Relay I upon becoming energized, completes its own 45 stick circuit passing from terminal b, through contact 40 of relay R contact 45 of relay I the Winding of relay I and push button contact U to terminal 0. The westbound train, while proceeding over switch F forces switch F to the reverse position since dog a is now out of engagement with bar (1.

This train, upon entering section AB, deenergizes relay R thereby causing a second stick circuit to be completed for relay I passing from terminal b through contact 43 of relay R contact 44 of relay H back point of contact 42 of relay P contact 45 of relay I the winding of relay I and push button contact U to terminal 0.

Relay 13 therefore continues energized after the train leaves section B-C. The circuit for relay P previously traced, therefore remains open at back contact I 4 of relay I and hence the re-' verse operating circuit for motor G remains open at contacts I! and '20 of relay P and thecircuit for relay H remains open at contact 27 of relay P thus causing signal S to continue to display a stop indication while the train is receding from this signal. 7 V

If, however, the train is to proceed eastward on track Y instead of continuing its westward movement, a trainman will now operate push button contact U to open the stick circuit for relay I Relay I upon becoming deenergized, permits relay P to become energized by its cirand contact 31 of relay I cuit previously traced, which thereupon causes motor G to lock switch F after which signal S will display its proceed indication.

I will now assume that a fast westbound train is to pass a slow westbound train. The slow train will be sent onto track Z, whereas the fast train willmove over track Y. The slow train having arrived on section C before the fast train has arrived on section CD, relay P will become energized by a second pick-up circuit which is the same as the pick-up circuit previously traced for this relay except that it includes contact 36 of relay R instead of contact 31 of relay I With relay P energized, motor G will operate to disengage dog a from bar d if dog a is not already in its unlocking position. As soon as dog a is out of engagement with bar d, relay H will become energized by its circuit previously traced. Under this condition, relay I remains deenergized, and the train on track Y deenergizes relay R and hence relay P becomes deenergized since it pickup circuits will be open at contact 36 of relay R With relay P deenergized, the circuit for relay H is opened at contact 48 of relay P and hence signal S will be caused to again display a stop indication. A circuit will now be completed, however, for energizing relay H passing from terminal I)", through contact 32 of relay P contact 33 of relay R contact 36 of relay R contact 38 of relay R contact 39 of relay I and the winding of relay H to terminal Relay H upon becoming energized, opens, at the back point of its contact II, the circuit for the red lamp of signal S and completes, at the front point of its contact I l, the circuit for the green lamp G of signal S When the westbound train on track Y enters section BC, a secondpick-up circuit will, on account of relay I-I being slow releasing, be completed for relay I passing from terminal b, through contact 49 of relay R contact 4| of relay 1-1 the winding of relay I and push button contact U to terminal 0. As the train proceeds westward through section A-B, relay I will continue energized by its second stick circuit previously traced, and will therefore prevent motor G from operating and signal S from clearing. When the fast train has left section AB, relay P will again become energized by its second pickup circuit, thereupon causing relay H to become energized, which will cause signal S to display-a proceed indication.

If, after all parts of the apparatus have again returned to their normal condition, an eastbound train enters section AB, causing motor G to operate dog a to lock bar d, and if it is then desired that this train shall move over switch F reversed to track Z instead of over its normal route to track Y, a trainman will insert crank N in the position in which it is shown in dash lines in the drawings, and will then operatecrank N to disengage dog a from bar 01. The placing of crank N in the position shown in dash lines opens contact 8, therebybreaking the stick circuit for relay I which, thereupon becoming deenergized, opens the operating circuits previously traced for motor G. Relay I can not again become energized, by its pick-up circuit previously traced, until the train has moved onto section BC, deenergizing relay R nor until after the trainman removes crank N from the position shown in the drawings. The energization of relay I will then cause relay R to become energized, after the train leaves section '.BC, by its pick-up circuit which includes contact of relay I Referring now to Fig. 2, all parts of the apparatus are shown in the normal condition, that is, switches F and F are in their normal position; each of the signals S S S and S is displaying a stop indication, and signals S and S are dis- 5 playing a clear indication; each of the track sections is unoccupied; each of the relays H, I- and W is deenergized except relay H and relays T are energized in the normal direction.

The circuit by which relay H is energized passes from terminal 12, through front point of contact 59 of relay R front point of contact 5| of relay T contact 41 of dog a, back point of contact 52 of relay I front point of contact 53 of relay R contact 54 of relay H and the winding of relay H to terminal 0. With relay T energized in the normal direction by its circuit, only a portion of which is shown, including contact 49 of relay R and with relay H energized, green lamp G of signal S is lighted by its circuit passing from terminal b, through the front point of contact H of relay H contact 8| of relay T in its normal position, and green lamp G of signal S to terminal 0. Green lamp G of signal S is lighted by a similar circiut not shown in the drawings. Relay T for controlling signal S is energized in the normal direction by a circuit passing from terminal 13 of a second source of current not shown in the drawings, through contact 63 of switch F front point of contact 68 of relay R front point of contact 10 of relay H contact 82 of relay R winding of relay T and the front point of contact 'H of relay H to terminal o of the second source of current.

I will now assume that an eastbound train deenergizes relay T which then opens, at the front point of its contact 5!, the circuit previously traced for relay H causing relay H to become deenergized. A circuit will be thereby completed for energizing control element 59 of time element device M, passing from terminal b, through the front point of contact 50 of relay R back point of contact 5| of relay T contact 55 of relay H contact 56 of relay H contact 51 of relay I back point of contact 58 of relay W control element 59 of device M, contact 1' of switch F contact 8 of crank N, and contact 2| of motor G in its normal position to terminal 0. Upon the lapse of a measured period of time after control element 59 becomes energized, contact 69 of device M will close, thereby completing a circuit for energizing relay W which is the same as the circuit traced for control element 59 of device M except that between contact 51 of relay I and contact I of switch F it passes through contact 69 of device M and the winding of relay W Relay W upon becoming energized, completes its own stick circuit which is the same as its pick-up circuit just traced except that it includes the front point of its own contact 58 instead of contact 60 of device 60 M. The opening of contact 58 of relay W at its back point deenergizes control element 59 of device M. Relay W upon becoming energized. completes a reverse operating circuit for motor G, passing from terminal I), through the front point of contact 5! of relay W armature l8 of motor G, back point of contact 62 of relay W and field winding 22 of motor G to terminal 0. Motor G thereupon moves dog a into engagement with bar (2. Motor G, through its contact 2|, opens the circuit traced for relay W causing this relay tobecome deenergized when dog 0. reaches its final position for locking bar (1.

Upon the completion of this operation of dog a, acircuit is completed for relay H passing from 'of the first reverse energizing circuit. upon becoming energized, also completes a pickup circuit for. relay I passing from terminal I), through contact 73 of relay I winding of relay I and push button contact U to terminal 0.

of relay T in its normal position.

The deenergization of relay H when relay T becomes deenergized, causes contacts l0 and H of relay H to reverse the polarity of the current supplied to relay T by the circuit previously traced.

The train, upon entering section BC, deenergizes relay R which thereupon opens, at the front points of its contacts 66 and 58, the circuits traced for relays H and T respectively, causing these relays to become deenergized. Re-

lay H is, however, slow releasing, and hence a pick-up circuit for relay I is closed for a brief period of time, said circuit passing from terminal 17, through contact 28 of relay R contact 66 of relay H and the winding of relay I to terminal 0. Relay I upon becoming energized, completes its stick circuit which is the same as the pick-up circuit just traced except that it includes, contact 3| of relay I instead of contact 66 of relay H Relay I upon becoming energized, completes a second reverse energizing circuit for relay Tfiwhich includes contact 69 of relay I instead of the front point of contact 68 of relay R Relay I As the train proceeds further and enters section C-D, deenergizing relay R relay T becomes deenergized on account of the opening of contact 49 of relay R Relay R at this time also completes a stick circuit for relay 1, said circuit passing from terminal b, through contact 14 of relay R contact of relay I winding of relay I and push button contact U to terminal 0. Relay I therefore remains energized as the train proceeds eastward through section C-D. The energization of relay I holds open, at the back point of its contact 52, the circuit for energizing relay H and hence signal S will not clear While the eastbound train is in section C-D.

When the train has left section BC, relay W becomes energized by a circuit passing from terminal I), through the front point of contact 50 of relay R front point of, contact 5! of relay T winding of relay W ,'and contact 2! of motor G in its reverse position. Relay W upon becoming energized, completes a normal operating circuit for motor G, said circuit passing from terminal 11, through the front point of contact 62 of relay W armature l8 of motor G, back point of contact SI of relay W and field winding 22 of motor G to terminal 0. Motor G thereupon operates dog a cut of engagement with bar 12.

I will now assume that all parts of the apparatus have again been returned to their normal condition, and that a westbound train passes signal S which is now displaying a proceed indication. Relay R thereupon becomes deenergized, opening, at the front point of its contact 50, the circuit previously traced for relay H and thereby causing relay H to become deenergized. Relay H being slow releasing, a pick-up circuit for relay I will be completed for a brief period, said;

circuit passing from terminal I), through the back point of contact 50 of relay R front point of cone tact 19 of relay H winding of relay I and push button U to terminal 0. The energization of relay I causes a stick circuit to be completed for this relay, which is the same as the pick-up circuit just traced except thatit includes contact 45 of relay I instead of contact 19 of relay H As the train proceeds further and enters section A-B, a second stick circuit is completed for relay I said circuit passing from terminal b, 1

through contact 11 of relay T back point of cone,

tact 18 of relay H back point of contact 19 of re lay H contact 45 of relay I winding of relay vI and push button contact U to terminal 0.

Relay I will, therefore, continue, energizedas 1 long as relay R is deenergized, unless a trainman opens the stick circuit for relay I by operating push button U in the manner described in connection with Fig. 1. Motor G will, therefore,

not be operated to move dog a into engagement 20 with bar (1, and signal S will not be cleared,

while the train is receding from signal S From the foregoing description and the accompanying drawings, it follows that each of a few forms of apparatus embodying my invention com- 2.,

prises a track switch which is biased to a normal position, and which may bed the well known spring switch type; a device automatically operated for locking this switch in its normal position; an automatically operated trafiic governing device for authorizing traflic movements in the facing direction over the switch, while the switch is in its normal position, if and only if the switch is locked; and an automatically controlled tralfic governing device for authorizing traflic movements in the trailing direction over the switch if and only if the switch is unlocked.

I have described, for a few typical trafiic movements, the operation of a few forms of apparatus embodying my invention. From these descriptions and from the accompanying drawings, the operation of the apparatus for every other possible traflic movement may be readily determined.

Although I have herein shown and described only two forms of railway trafiic controlling apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing .from the spirit and scope of my inyention.

Having thus described my invention, what I claim is: i

1. In combination, a railway track switch,

means set into operation by a train approaching said switch from a given direction for locking said 5 switch, a signal for governing traflic movements from said given direction over said switch, means set into operation by a train approaching said switch from said given direction for clearing said signal only if said switch is locked by said switch locking means, means set into operation by a train approaching said switch from a second direction for unlocking said switch, a second signal for governing trafiic movements from said second direction over said switch, and means set into operation by a train approaching said switch from said second direction for clearing said second signal only if said switch is unlocked.

2. In combination, a railway track switch, means for at times locking said switch, means set into operation by a train approaching said switch for unlocking said switch, a signal for governing trafiic movements over said switch, and means set into operation by a train approaching said switch for clearing said signal only if said switch 75 is unlocked and for completing the clearing of said signal only if said switch remains unlocked.

3. In combination, a railway track switch, means set into operation by atrain approaching said switch from a given direction for locking said switch, means set into operation by a second train approaching said switch from a second direction for unlocking said switch, and directional means controlled by said second train for preventing operation of said locking means for lock ing said switch when said second train recedes from said switch.

4. In combination, a railway track switch, means set into operation by a train approaching said switch from a given direction for locking said switch, a signal for governing traffic movements from the opposite direction over said switch, means set into operation by a train approaching said signal from said opposite direction for clearing said signal, and directional means set into operation by a train moving over said switch from said first direction for preventing said signal from clearing when the train moving from said first direction recedes from said signal.

5. In combination, a railway track switch, means for at times locking said switch, a signal for governing trafiic movements over said switch, a second signal for governing trafiic movements over said switch, means set into operation by a train approaching said first signal for clearing said first signal only if said switch is locked, and means set into operation by a train approaching said second signal for clearing said second signal only if said switch is unlocked.

6. In combination, a railway track switch, an approach track section adjacent said switch, a time element device, means for energizing said time element device when a train enters said ap proach section if said switch is in the normal position, a switch relay, a circuit controlled by said time element device for energizing said switch relay upon the lapse of a measured period of time after said time element device becomes energized, and a circuit including a front contact of said switch relay for locking said switch in said normal position.

7. In combination, a railway track switch, a contact operated by said switch and arranged to be closed if and only if said switch is in its normal position, a locking device for locking said'switch, an approach relay energized by a train approaching said switch, and a circuit including said switch operated contact and a front contact oi said approach relay for operating said locking device to lock said switch.

8. In combination, a railway track switch, a contact operated by said switch and arranged to be closed if and only if said switch is in its normal position, a locking device for locking said switch, an approach relay energized by a train approaching said switch, a circuit including said switch operated contact and a front contact of said approach relay for operating said locking device to lock said switch, a signal for governing traffic movements over said switch, and a circuit including a front contact of said approach relay and closed if and only if said switch is locked for clearing said signal.

9. In combination, a railway track switch, means for at times locking said switch, an approach relay energized if a train approaches said switch, a circuit including a front contact of said relay for operating said locking means to unlock said switch, a signal for governing trafiic movements over said switch, and a circuit including a front contact of said approach relay and closed if and only if said switch is unlocked for clearing said signal.

10. In combination, a railway track switch, a control relay, a second control relay, means for selectively energizing said control relays, an electric circuit controlled by said first relay forlooking said switch for trafiic movements in a given direction over said switch in a given position when and only when said second relay is deenergized, and an electric circuit controlled by said second relay for unlocking said switch and for leaving said switch in the unlocked condition for trafiic movements in the opposite direction over said switch in said given position.

11. In combination, a railway track switch, a normally energized relay deenergized by a train approaching said switch, a time element device. means controlled by said relay for setting said time element device into operation when said relay becomes deenergized, and means controlled by said time element device for locking said switch upon the lapse of a measured period of time after said relay becomes deenergized.

12. In combination, a railway track switch, a time element device, means controlled by a train approaching said switch for setting said time element device into operation, and means controlled by said time element device for locking said switch upon the lapse of a measured period of time after said time element .device is set into operation.

HENRY S. YOUNG. 

